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Патент USA US3098273

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July 23, 1963
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3,098,263
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July 23, 1963
w. B. CAMPBELL
3,098,253
APPARATUS FOR MOLDING A BALL AND SOCKET JOINT ASSEMBLY
Filed June 22, 1960
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4 Sheets-Sheet 2
July 23, 1963
w, B, CAMPBELL
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3,098,263
APPARATUS FOR MOLDING A BALL AND SOCKET JOINT ASSEMBLY
Filed June 22, 1960
4 Sheets-Sheet 5
July 23, 1963
w. B. CAMPBELL
3,098,263
APPARATUS FOR MOLDING A BALL AND SOCKET JOINT ASSEMBLY
Filed June 22, 1960
4 Sheets-Sheet 4
4 646°
31
/
/34
United States Patent 0
3,098,263
1,
lC€
Patented July 23, 1963
1
2
3,098,263
other parts of the mold section. In the preferred form of
the invention, the ball stud is supported within the mold
by hydraulic means.
APPARATUS FGR MOLDING A BALL AND
SOCKET JOINT ASSEMBLY
William B. Campbell, Haddon?eld, N.J., assignor, by
mesne assignments, to Garlock Inc, Palmyra, N.Y., a
corporation of New York
Filed June 22, 1960, Ser. No. 38,058
6 Claims. (Cl. 18-36)
For a more detailed description of the invention and for
further objects and advantages thereof, reference is to be
had to the following description taken in conjunction with
the accompanying drawings in which:
FIG. 1 is an elevation view of an injection molding
machine including a mold embodying the present inven
This invention relates to an apparatus for molding a 10 tion;
ball and socket joint assembly and has for an object a
FIG. 2 is a top plan view of the mold taken along the
system for providing an improved ball and socket joint
lines 2-2 in FIG. 1 with portions thereof broken away
assembly wherein the plastic lining of the assembly is
for clarity;
FIG. 3 is a sectional view taken along the lines 3-3 in
molded in situ.
This invention is particularly directed to the manu 15 FIG. 2;
facture of ball and socket joint assemblies adapted for
FIG. 4 is a view taken along the lines 4—4 in FIG. 2;
use in suspension and stabilization of automobiles. In
FIG. 5 is a view taken lalong the lines 5-5 in FIG. 2;
the past it has been the practice to provide ball ‘and socket
and
joint assemblies either with metal to metal contact or with
FIG. 6 is a sectional view taken along the lines 6-—'6
a lining material such as a moldable non-metallic high
in FIG. 2.
impact material. In the case of the latter, it has been the
Referring to the drawings there is shown in FIG. 1 an
practice to mold the lining material around the ball por
injection-molding machine ll} of Well-known type and
tion of the stud and then to assemble the housing or socket
suited for molding in situ the plastic linings for universal
over the lining material. This manner of constructing
joints such as the ball joint assemblies adapted for use in
ball and socket joint assemblies utilizes a plurality of oper 25 suspension mechanisms of automobiles. One form of ball
ations and leaves much to be desired in obtaining a good
joint assembly is shown in FIG. 3 and consists of a stud
?t between the lining and housing and one which will be
member 11 having a ball-shaped end 11a which is adapted
to be received within a housing 12. A cover 13 is adapted
continuous in compensating for wear. It is desirable to
produce a joint of uniform torque and decrease these oper
to be secured to the upper end of the housing 12. The
ations to a minimum in order to minimize the cost of 30 cover 13 has an opening 13a therein through which a suit
the assembly.
Such assembly costs can be reduced by
able injection-moldable thermoplastic material is adapted
eliminating at least one of the assembly operations and
this can be acomplished by molding the plastic liner in
to be forced under pressure to provide a plastic liner be_
tween the portion 11a of stud 11 and the housing 12 and
‘cover 13. The injection-moldable thermoplastic material
'situ between the ball portion of the stud and the housing
or socket. Such molding operation presents a number 35 should have the characteristics of being resistant to impact,
of problems. One of the problems is to minimize the
heat and cold and corrosion, and mold'able with a re
sulting controlled torque to provide a dry-bearing material
shrinkage of the plastic when it contacts the metal parts
of the assembly ad a second problem is to enable the
which is noise-free in operation. Two examples of suit
same mold to produce satisfactory parts when parts of
able materials are a glass-?lled acetal resin sold under the
trademark “Delrin” and a glass-?lled polyamide sold un
either the maximum or minimum tolerances are used.
der the trademark “Nylon.” It is to be understood that
These problems are overcome by the present invention and
other equivalent injection-rnoldable thermoplastic mate
the resulting ball joint assembly has a perfect ?t between
the plastic liner and the metal parts regardless of their
rials having the aforesaid characteristics may be used.
speci?c dimensions within the maximum and minimum 45 The present invention is not directed to the ball joint as—
tolerances.
sembly per se, but instead is vdirected to the method and
In accordance with the present invention there is pro
vided a system for making a ball joint assembly including
apparatus for making such ball joint assembly.
stud. The ball stud is supported in the mold cavity in
spaced relation with the housing preparatory to receiving
a plastic material therebetween. Another mold section is
disposed adjacent the cavity mold section in face to face
having been shown in ope-nind position in FIG. 1. 'In
As may be seen in FIG, 1, the injection-molding ma
chine 18 is of the type which injects a heat-softened and
a mold having a plurality of sections one of which is pro
vided with a mold cavity adapted to receive a ball stud 50 ?owable material, such as the materials described above,
from a heating cylinder 15 into a die or mold 16, the latter
and a housing surrounding a portion of the ball on the
FIG. 2 the die or mold 16 is shown in closed position.
The mold ‘16 is adapted to be clamped between a pair of
clamping members 18, 18’ of conventional construction
and which’ comprise part of the molding machine 10*.
relation and is adapted to maintain a cover in predeter
These clamping members 18, 13' are associated with an
mined relation with the housing. This mold section in
hydraulic cylinder 20 of machine is which is adapted to
cludes spring-biased means movable within an enclosure
apply clamping pressure to the mold 16 in the order of
formed between the mold sections and engaging the cover
to permit the respective faces of the mold sections to be 60 several tons, such for example as about 75 tons. The in
jection-moldable plastic material in the form of molding
maintained in tight engagement while accommodating as
granules is placed into a hopper 22 on the machine It}
sembled covers and housings of the ball joint assembly
from which they are fed into the heating cylinder 15. The
within a predetermined tolerance. The spring-biased
cylinder 15 is provided with a plunger (not shown) which
means has an area less than that of the face of one of the
molded sections and as great as that of the cover. The 65 forces the material into the mold 16 by way of a dis
spring-biased means has an opening therethrough for pas
sage of the plastic material between the mold sections
and into the spacing formed between the ball stud and
housing. The mold section which receives the cover in
charge nozzle 24. The temperature within the cylinder
15 is maintained at a predetermined level. by electric
heating units or other suitable means well-known in the
art. The temperature of the mold 16 is lower than the
cludes a spring-biased sprue bushing extending through 70 softening point of the plastic material and thus the mold
rapidly absorbs heat from the soft plastic material causing
the opening in the spring-biased means and engageable
it to harden.
with the cover and movable independently relative to the
8,098,263
Referring to FIGS. 2 and 3, it will be seen that the mold
16 includes a cavity section 26 and a force retainer plate
section 27. The cavity section 26 is adapted to receive
the housing 12, FIG. 3, of the ball joint assembly and also
the ball stud member 11. The ball stud member 11 is
supported in spaced relation to the interior of the housing
12 by means of a retainer sleeve insert 29 which in turn
is supported by a retainer sleeve 30 which extends through
an opening in the cavity section 26. The rear end of the
that in FIG. 3 that the head portions of the screws 42 are
spaced above the mold section 27 a distance correspond
ing approximately to the depth of the recess 26b in mold
section 26.
The mold section 27 is provided with a sprue bushing 45
which has a passage 45a itherethrough for passage of the
plastic from the nozzle 24 to the ori?ce or opening 13a
in the cover member 13. It will be noted that the sprue
bushing at its opposite ends is in tight engagement with
retainer sleeve 30, i.e., the end remote from the ball stud 10 the nozzle 24 and the surface of cover member 13 sur
11 is held against a sleeve knockout plate 32 by means of
rounding the opening 13a. This condition must be ob
a sleeve retainer plate 33. The sleeve knockout plate 32
tained for all ball joint assemblies within the permissible
extends completely across the mold 16 as shown in FIG.
tolerance range. Otherwise, the plastic material would be
2 and the outer ends of ‘the plate 32 are connected to hy
forced between any space appearing between the cover 13
draulic cylinders 34 at opposite sides of the mold. The 15 and the adjacent end of the sprue bushing 45. To insure
plate 32 is provided with a pair of guide pins 36 which are
the tight engagement of the sprue bushing 45 with the
disposed on opposite sides of the retainer sleeve 30, FIG.
cover 13, as shown in FIG. 3, the sprue bushing is con
6. These guide pins 36 guide the knockout plate 32 during
structed so that it is movable relative to the force plate 39
its movement by the hydraulic cylinders 34. The purpose
against the bias of disc spring washers 47 which are adapt
of the hydraulic cylinders 34 will later be described.
ed to be compressed between the external shoulder 45b
The cavity section 26 of mold 16 is supported from a
on the sprue bushing 45 and the internal shoulder 27a
clamp plate 18a by means of a pair of support rails 35 and
formed at the bottom of the recess in the mold section 27.
screw members 29, FIG. 3. The force retainer plate sec
When the mold sections 26 and 27 are in closed position,
tion 27 of the mold is supported by another clamp‘ plate
as shown in FIG. 3, the cover member 13 will move
18b by means of screws 31, FIG. 2. The clamp plates 25 against the adjacent end of the sprue bushing 45 causing
18a and 18b are adapted to be secured to the respective
the disc washers 47 to be compressed in the manner illus
trated.
clamping members 18, 18' of machine 10. The clamp
plate 18b has a locating ring 37 through which the nozzle
Referring to FIG. 1, it will be recalled that the mold
24 is adapted to extend. The retainer plate section 27 is
16 is shown in open position with the movable mold sec
provided with a recess which is adapted to receive a force 30 tion 26 spaced from the ?xed mold section 27. A plu
plate 39, FIG. 4, the outer surface of which is shaped for
rality of leader pins 49 interconnect the mold sections 26
conformity with the abutting surface of the cover mem
and 27 with the mold 16. These leader pins 49 are re
ber 13 of the ball joint assembly, FIG. 3.
tained in the ?xed section 27 of the mold between the
As may be seen in FIGS. 3 and 5, the cavity section 26
clamp plate 18b and the mold section 27, FIG. 2. It will
of the mold 16 is provided with a cavity or recess 26a 35 be noted that the leader pins 49 are provided with a head
which is shaped to receive the housing 12 of the ball joint
49a to prevent them from being displaced from the mold
assembly. As may be seen in FIG. 3, the ?anged portions
section 27. The mold section 26 is provided with mating
12a and 13a of the housing and cover of the ball joint as
openings or passages 50 for receiving the respective leader
sembly are adapted to be positioned between the opposing
pins 49. The passages 50 are each lined with bushings 51
surfaces of the mold sections 26 and 27. This surface of 40 which have an internal diameter of sut?cient dimension to
mold section 27 is located on the force plate member
provide a slip ?-t with the leader pins 49.
39. The combined ‘thickness of the ?ange portions 12a
The mold section 26 is adapted to be moved to the right,
and 13a of the ball joint assembly may vary within a pre
as shown in FIG. 1, until it is in engagement with the sta
determined tolerance and still be satisfactory for use in
tionary or ?xed mold section 27. At this time the various
suspension mechanisms of automobiles. -It is desirable 45 parts will assume the positions shown in FIG. 2. A pre
that this tolerance be as wide as possible in order that the
determined quantity of the plastic material is then injected
cost of manufacturing the housing 12 and cover members
under high pressure into the mold 16 by way of the nozzle
13 may be kept to a minimum. The present invention
24, FIG. 3. This predetermined quantity is adequate to
enables the same mold to accommodate all sizes of hous
completely ?ll the space between the ball portion 11a of
ing and cover parts within the foregoing broad tolerances. 50 stud 11 and the adjacent interior surfaces of housing 12
To accomplish this, the rear surface of the force plate 39
and cover 13, thus providing a plastic liner 14 which,
is provided with a plurality of recesses 39a which are dis~
either with or without an inner liner, completely ?lls the
posed around the center of the member 39 and are adapted
spacing between the metal parts of the ball joint assembly.
to receive a series of disc-type spring washers 41. The
By molding the plastic liner 14 in situ, there is eliminated
washers 41 are positioned on a series of screw members 42 55
which extend through openings 43 in the mold section 27
and are provided with threads at their outer ends which
are secured to the force plate 39 and retain the latter in
the mold section 27. It will be noted in FIG. 3 that the
ball joint assembly illustrated therein includes a housing 60
12 and cover 13 having ?anges 12a and 13a of a total
thickness corresponding to the maximum tolerance dimen
sion. Thus the force plate 39 is pressed against the mold
the subsequent assembly operation heretofore employed in
ball joint assemblies such, for example, as the type de
scribed in Baker, Patent No. 2,879,091, thus minimizing
assembly costs and at the same time providing an improved
ball joint assembly construction.
Before the metal parts of the ball joint assembly i.e.,
the ball stud 11, either with or without an inner liner,
the housing 12 and the cover 13 are placed in the mold
16; they are soaked in an electrically-heated oven to
bring their temperatures up to about 250° F. to 275° F.
section 27 and the washer members 41 are in compressed
condition. It will be noted that the mold sections 26 and 65 This temperature is critical with respect to the speci?c
27 are in tight engagement with each other. When a ball
plastic materials mentioned above and if signi?cantly
joint assembly having a ?ange thickness corresponding to
the minimum tolerance dimension is inserted in the mold,
the washers 41 will force the force plate 39 outwardly of
lower or higher temperatures are used, the molding opera
tion cannot be performed satisfactorily. Adequate con
trol of torque on the molded parts is also a function of
mold section 27 into the recessed portion 26b of the cavity 70 of the pressure applied to the molding compound during
mold section 26 and tightly against the exposed or adja
the actual injection process. It has been found that the
cent surface of the cover member 13. By providing the
best control is obtainable when the parts are molded with
mold section 26 with the recess portion 26b, the force
a slight “cushion” of molding compound with the injec
plate 39 does not interfere with the closing or mating of
tion plunger in the advanced position. The sections 26
the two mold section members 26 and 27. It will be noted 75 and 27 of the mold 16 are maintained at a predeter
3,098,263
5
.
mined temperature during the molding process by means
6
out pins 66 corresponds to the spacing illustrated in 'FIG.
2 between the adjacent surfaces of retainer member 65
of a heated liquid, such as oil, which goes through inter
and the left-hand end of section 26. When these two
nal passages 26p and 27p in sections 26 and 27. The
surfaces are in engagement, the molded ball joint assem
passages 26p in mold section 26 are connected with inlet
and outlet pipes 55‘ and 56, FIG. 5. The passages 26p Cl bly will have been ejected from the cavity in mold sec
tion 26.
are sealed from the exterior of the mold section 26 by
At this time it will be noted that the guide pins 68
suitable pipe plugs 57. Similarly in FIG. 4, the ?ow
which are carried by the knockout plate 64 will have been
passages 27p are provide-d with inlet and outlet pipes 58
moved to the right from their position illustrated in FIG.
and 59 which are connected to a suitable source of
heated liquid and the passages 27p are sealed from the 10 2 so that they will extend beyond their passages in mold
cavity 26. These guide pins 68 "are adapted to return
exterior of the mold section 27 by suitable pipe plugs 57’.
the knockout plate 64 and the retainer plate 65 to their
The liquid, which is adapted to pass through the ?ow pas
original positions against backstop members 69 which
sages 26p and 27p preferably is oil heated to a tempera
ture of approximately 275° F. to 300° F. This insures
are secured, as by screws 70, to the support rails 35,
that the mold will be maintained at a predetermined tem 15 FIGS. 2, 3 and 6, as shown in FIG. 2. This takes place
in the following manner: When the mold section 26 is
perature below the temperature of the molding compound
moved to the right from the open position shown in FIG.
being injected into the mold and thus causing the molding
1, to the closed position shown in FIG. 2, to perform
compound to harden in a predetermined length of time.
a subsequent molding operation, the guide pins 68 will
The purpose of this pre-heating is two-fold in that it
?rst engage the abutting surface of the stationary mem
permits a better ?ow of plastic material into the housing
ber section 227. As the mold section 26 continues to move
12 and around the stud 11 and additionally it expands all
to the right towards closed position, for the mold, the
the metal parts, 11, 12 and 13. After the molding opera
pins 68 will cause the knockout plate 64 and the retainer
tion is completed, the metal parts, 11-13, contract as the
65 to move to the left until they occupy the position
molding compound 14 goes through its phase of mold
shrinkage. If the metal parts of the assembly are not 25 shown in FIG. 2 against the backstop members 69 with
the mold sections 26 and 27 in closed or clamped posi
pro-heated, it is impossible to control the torque of the
assembly after molding.
,
tion. At this time the spacing between the knockout
plate 64 and the ?xed knockout plate 62, FIG. 1, is
As mentioned above, the support 30 for the ball stud
_ greater than the overall length of the knockout rods 60,
11 is carried by a sleeve knockout plate 32 which in
the latter being free to slide in their openings in the clamp
turn is connected to hydraulic cylinders 34 at the oppo
plate 18a between the knockout plates 62 and 64.
site sides of the mold. The hydraulic cylinders 34, in
While the preferred embodiment of this invention has
combination with the spring loading of the force plate 39,
been illustrated, it is to be understood that other modi?
enable the mold to fully compensate for the range of di
cations thereof may be made within the scope of the
mensional tolerances on the cover and housing parts 12
and 13 of the ball joint assembly. The ball stud assem
appended claims.
bly is placed in the mold with the hydraulic cylinders 34
What is claimed is:
1. Apparatus for making a ball joint assembly com
in forward position. The total force available by this
prising a mold including a plurality of sections, one of
hydraulic action is suf?cient to withstand opposing pres
said sections having a mold cavity shaped to receive a
sure of the plastic material as it is injected into the
ball stud and a housing surrounding a portion of the ball
cavity. If, however, the parts are su?iciently oversized,
on the stud, means in said mold cavity for supporting the
the clamping pressure of the press which greatly exceeds
ball stud in spaced relation with the housing preparatory
the injection pressure, is su?icient to cause the hydraulic
cylinders 34 to drift back slightly to compensate still
to receiving a plastic material therebetween, another mold
section disposed adjacent said ?rst-named mold section
further for irregularities in dimensions.
in face to face relation and adapted to maintain a cover
‘It will now be assumed that the molding process has
in predetermined relation with the housing, said last
been completed and the mold or die 16 is to be moved
named section including spring~biased means for engag
from its closed position, shown in FIG. 2, to its open
ing the cover and having an area less than that of the
position, shown in FIG. 1. The movable section 26 of
the die moves to the left as shown in FIG. 2 under the
face of said last-named mold section and as great as that
control of the hydraulic cylinder 20, FIG. 1. This move 50 of the cover, said spring-biased means having an opening
therethrough for passage of the plastic material between
ment causes the knockout rods 60, which are loosely
said mold sections and into the spacing formed between
carried by passages 18p in clamp plate 18a, to be en
the ball stud and housing, said spring-biased means being
gaged at their rear ends by a stationary knockout plate
62 carried by and which forms part of the molding ma
movable within an enclosure formed between said mold
chine 10, FIG. 1. The forward ends of the knockout 55 sections and permitting the respective faces of said mold
rods 60 engage a knockout plate 64 which is provided
sections to be maintained in tight engagement while ac
commodating assembled covers and housings of the ball
with a retainer 65 for holding a pair of knockout pins
66. The ends of these pins 66 are adapted to engage
joint assembly within a predetermined tolerance.
two of the corners of the. housing 12 for the ball joint
2. Apparatus according to claim 1 wherein said last
assembly, as shown in FIG. 5. Only one of the knock 60 named mold section includes a spring-biased sprue bush
ing extending through the opening in said spring-biased
out pins 66 appears in FIG. 2. As the movable section
26 of the mold moves further to the left and thus away
means to engage the cover and movable independently
from the stationary section 27, the knockout plate 64
relative to the other parts of said last-named section.
3. Apparatus according to claim 1 including hydraulic
causes the knockout pins 66 to push the molded ball joint
assembly from its cavity in mold section 26, FIG. 3. 65 means for supporting the ball stud within said mold.
As may be seen in FIG. 2, the pins 66 are provided with
4. Apparatus for molding in situ a plastic liner for a
a shoulder which engages the lower surface of the flange
ball joint assembly of the type including a ball stud sur
portion 12a of the housing 12. Concurrently with this
rounded by the plastic liner and enclosed within a hous
action the hydraulic cylinders 34 cause the knockout
ing and a cover, the housing and cover having a thickness
plate 32 to force the ball joint assembly out of the cavity 70 within a predetermined tolerance range, comprising a
in mold section 26 along an inclined axis whereas the
mold including a plurality of sections, one of said sec
tions having a mold cavity adapted to receive the ball,
knockout pins 66 act along a horizontal axis. This com
stud and a housing surrounding a portion of the ball on
bined knockout action enables the completed ball joint
the stud, means extending into said one section for sup
assembly to be quickly and readily removed from the
mold cavity. The distance of movement of the knock 75 porting the ball stud in spaced relation with the housing
3,098,263
7
8
preparatory to receiving a plastic material therebetween,
of the metal parts and coextensive in area therewith to
maintain it in predetermined relation with the other metal
a second mold section disposed adjacent to said ?rst
named mold section in face to face relation, said second
mold section including a force plate having an area less
than that of the face of said second mold section and as
great as that of the cover and adapted to maintain the
cover in predetermined relation with the housing, said
force plate being movable within an enclosure formed
between said mold sections, said force plate having an
part, said force plate having an opening therethrough for
passage of the plastic material between said mold sections
and into the spacing formed between the two metal parts,
said force plate being movable within an enclosure formed
between said mold sections, compression spring means
disposed between said second section and said force plate
permitting the respective faces of said mold sections to be
opening therethrough for passage of the plastic material 10 maintained in tight engagement and concurrently per
between said mold sections and into the spacing formed
mitting said force plate to adjust its position relative to
between the ball stud and housing, compression spring
said second mold section to accommodate assembled
means disposed between said second section and said
metal parts of the joint assembly within the predeter
force plate permitting the respective faces of said mold
mined tolerance range.
sections to be maintained in tight engagement and con 15
currently permitting said force plate to adjust its position
within said enclosure relative to said second mold section
to accommodate assembled covers and housings of differ
ent thicknesses for the ball joint assembly within the pre
determined tolerance range.
20
‘5. Apparatus according to claim 4 wherein said force
plate is carried by a plurality of fastener members ex
tending through said second mold section and said com
pression spring means comprises a plurality of spring
members disposed on said fastener members between said 25
second mold section and said force plate.
6. Apparatus for molding in situ a plastic liner for a
joint assembly of the type including at least two engaged
metal parts enclosing the plastic liner, the metal parts
having a combined thickness which may vary within a 30
predetermined tolerance range, comprising a mold includ
ing a plurality of sections, one of said sections having a
mold cavity adapted to receive the metal parts and sup
port them in predetermined spaced relation preparatory
References Cited in the ?le of this patent
UNITED STATES PATENTS
‘1,846,482
2,241,180
2,265,995
2,443,826
2,473,481
2,483,093
2,587,070
2,655,692
2,891,283
2,954,992
2,961,704
2,979,772
2,999,273
Fiegel _______________ __ Feb. 23,
Burke ________________ .. May 6,
Begerlein ____________ __ Dec. 16,
Johnson ______________ __ June 22,
Tobener _____________ __ June 14,
Harvey _____________ __ Sept. 27,
Spillman _____________ __ Feb. 26,
Fay _________________ __ Oct. 20,
Cramer et a1 __________ _- June 23,
Baker ________________ __ Oct. 4,
White _______________ __ Nov. 29,
MoslO _______________ __ Apr. 18,
Gronemeyer et al ______ .._ Sept. 12,
‘1932
1941
1941
1948
1949
1949
1952
1953
1959
1960
1960
‘1961
1961
1,123,873
France _______________ __ June 18, 1956
FOREIGN PATENTS
to receiving a plastic material therebetween, a second 35
OTHER REFERENCES
mold section disposed adjacent said ?rst-named mold sec
Plastics
Engineering
Handbook, Society of the Plastics
tion in face to face relation, said second mold section in
Industry, 1954, page 494.
cluding a force plate adapted to engage the adjacent one
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